Chromatography is a method in which the individual molecule types that make up a liquid or gaseous solution are separated. The way it works is that there are to phases that the solution interacts with; a stationary phase, which doesn't move, and a mobile phase, which flows through or past the stationary phase. The individual molecules in the solution with have their own specific amounts of affinity for the two phases. Those molecules with high affinity for the stationary phase and low affinity for the mobile phase will move through the column or paper or whatever the stationary phase is contained in or made up of slowly, while those with higher affinity for the mobile phase and lower for the stationary phase will move through it faster. It's similar to a filter in that a filter separates things, but a filter works more by immobilizing part of a mixture and letting another part pass through, as opposed to modifying the speeds at which parts of a solution move through the column (or whatever).

In layman's terms, it separates chemicals out according to their density, which also tends to do so according to color. More often than not, paper chromatography is done, which is when a drop of the solution in quesion is placed on an upright piece of special paper. Through capillary action, the liquid will rise up through the paper at different rates.

biostudent84 wrote:In layman's terms, it separates chemicals out according to their density, which also tends to do so according to color. More often than not, paper chromatography is done, which is when a drop of the solution in quesion is placed on an upright piece of special paper. Through capillary action, the liquid will rise up through the paper at different rates.

Except that paper chromatography is not the most frequently used in labs now. They prefer those fancy gas cromatograph, or High pressure liquid chromatographs to paper strips. And it looks better to ask for >50K$ machine than for whatman paper on grant applications, that makes you serious